Effect of impurity ions on preparation of novel saponifier for rare earth extraction

Magnesium bicarbonate, prepared by the carbonation of magnesium hydroxide slurry, was used as a novel saponifier to eliminate the ammonia nitrogen pollution in the rare earth extraction separation process. The effect of impurity ions introduced by system on the carbonation reaction of magnesium hydroxide was studied in the work. The results showed that the presence of Ca2＋could lead to side reactions so as to reduce the conversion rate of magnesium hydroxide, and a small number of rare earth ions would have great influence on the carbonation reaction. What’s more, there was no influence on carbonation reaction with the low concen-tration of Na＋or Mg2＋, the conversion rate of magnesium hydroxide could reach above 96%. This paper showed a practical theory which could provide scientific guidance for the preparation of novel saponifier in rare earth extraction separation process.

Quantification of Lipid Content and Identification of the Main Lipid Classes Present in Microalgae Extracts Scenedesmus sp. for Obtaining Fatty Compounds for Biofuel Production

Microalgae biomass has been reported in the literature as one of the most promising sources for obtaining different products of industrial interest such as lipids, fatty acids, carotenoids, proteins and fibers. The lipid fraction of microalgae comprises neutral lipids, free fatty acids and polar lipids. It is of great importance to estimate the composition of the lipid fraction to define the potential for use, either as a raw material for the production of biofuels or for use for nutraceuticals and/or food purposes. The microalgae Scenedesmus sp. cultivated in a photobioreactor, the sky open raceway type, was evaluated for lipid content, identification and quantification of lipid components obtained from different extracts. In the quantification of the lipid content, extraction methods were proposed without chemical treatment (use of solvents only) such as chloroform:methanol (2:1 v/v)—Bligh & Dyer, Ethanol, Ethyl acetate:Hexane (1:1 v/v) and others with chemical treatment such as J-Schmid-Bondzynski-Ratzlaff (acid) and saponification (basic). For the identification of the main lipid components present in the extracts, the Thin layer chromatography (TLC) technique was used. This made it possible, using a simple and inexpensive method, to identify the compounds extracted by different extraction methods, that is, it was possible to verify the selectivity of the different extraction methods. In addition, it has been shown that using these methods, widely described in the literature as methods of extracting lipids in practice, extracts a wide diversity of compounds. The levels of lipids obtained via solvent extraction were up to 50% higher than those obtained with chemical treatment. In lipid extracts, obtained via solvent extraction, the presence of polar compounds, glycerides, carotenoids, pigments and sterols was identified, with up to 53% being composed of an unsaponifiable fraction, thus, presenting low selectivity for extracting fatty components. The acidic and basic treatments applied to the biomass of Scenedesmus sp. showed greater selectivity for obtaining fat components of 71.47% and 94.99%, respectively. The results showed that depending on the solvent/method used to quantify the lipids, the selectivity for obtaining the grease fraction, fundamental for conversion into biofuels, varies and the total lipid content may be overestimated.

Recovery of rare earths from spent FCC catalysts by solvent extraction using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester(EHEHPA)

A process to recover rare earth（RE） metals from spent fluid catalytic cracking（FCC） catalysts by solvent extraction was studied, using saponified 2-ethylhexyl phosphoric acid-2-ethylhexyl ester（EHEHPA or P507）. The recovery process involved three steps：（1） leaching REs（mainly lanthanum and cerium）;（2） solvent extraction by applying saponified P507-kerosene system;（3） stripping. Experiments to assure optimal operating conditions were conducted. Results indicated that RE metals could be recovered effectively from spent catalyst with saponified P507-kerosene-HCl system. At room temperature of 25 oC, 10 g spent catalyst with 110 m L of HCl（1 mol/L） could achieve a leaching efficiency of 85%. For extraction, initial pH value of 3.17, organic/aqueous ratio（O/A ratio） of 2：1 with an extractants＇ saponification rate of 20% could obtain 100% efficiency. In the stripping process, 1 mol/L HCl with O/A ratio of 1：1 led to a stripping efficiency of 96%. In the present study, RE metals from spent FCC catalysts were effectively recovered, which avoided wasting a large amount of RE resources. It provides a theoretical support for commercial recycling of RE resources.

Modeling and Optimization of Lipid Extraction Process from Municipal Secondary Sludge for Biodiesel Production

In the current study,the potentiality and optimization of lipid extraction from secondary sludge for biodiesel production were investigated.Four lipid extraction parameters were examined and used for process optimization and model development using Design of Experiment(DoE)method(namely methanol to hexane ratio-%,solvent to sludge ratio-ml/g,temperature-oC and extraction time-h).During the optimization process,free fatty acid(FFA)and saponifiable lipids(SLs)content of the extracted lipid were analyzed.The results revealed that,the maximum lipid extraction yield(Ylipid)predicted through numerically optimized conditions by the model for highest desirability(0.99)was 16.5%at methanol to hexane ratio(%)of 84%,solvent to sludge ratio(v/wt)of 45 ml/g,temperature at 90℃ for 6 hours extraction time.The extracted lipid contained a maximum amount of 31%(wt/wt)FFA,where palmatic acid was predominant.The FAMEs yield produced from ex-situ acid-catalyzed esterification/transesterification of the methanol-hexane co-solvent extracted lipid ranged between 4.5-5%(wt/wt)based on sludge weight.Fatty acid profile of FAMEs was found to be dominated by methyl palmitate(C16:0)representing 36%of FAMEs composition,followed by palmitoleic acid methyl ester(C16:1),oleic acid methyl ester(C18:1)and stearic acid methyl ester(C18:1)representing 24%,18%and 10%of the FFA composition respectively.PCA analysis showed that solvent to sludge ratio(ml/g)has the highest significant positive effect on FAMEs yield(p-value<0.05)where methanol to hexane ratio(X1),temperature(X3)and extraction time(X4)were inversely correlated with FAMEs yield.The results indicated the feasibility of using secondary sludge as an alternative feedstock for biodiesel production.However,the optimized conditions for maximizing extracted lipid content should not be considered suitable for FAMEs yield as well.